In the upwardly acting door art, the door system typically includes a counter-balance assembly that is capable of generating a force to suitably offset the weight of the door, such that the door may be raised or lowered without undue effort from a person manually opening the door or a motorized operator system used to raise and lower the door. Typical counterbalance systems include an axle, which may be either a solid shaft or tube, having a torsion spring mounted thereon and interconnected with the door. The spring is tensioned to provide the appropriate variable counterbalancing force for the weight of the door where the door moves between a closed vertical position and an open horizontal position. In door systems using a motorized operator, it is common to use an operator mounted on the ceiling of the structure having a track extending toward the door and a trolley, which rides on the track, attached to the door to raise and lower the door by applying force directly to the door. It is also known to employ a “jack shaft” operating system that interacts with the counterbalance system to raise and lower the door. A jack shaft type operator has the advantage of eliminating the need for head space within the structure ordinarily occupied by a trolley-type operator and otherwise providing a more compact door system.
One known door design includes a jack shaft-type operating system for controllably moving in upward and downward directions a sectional door in relation to a door frame having a pair of jambs and an interconnecting header, including a counterbalance system having a drive tube interconnected with the sectional door proximate the ends thereof, a motorized operator mounted adjacent to the drive tube and between the ends of the sectional door and a drive train interconnecting the drive tube and the motorized operator for selectively driving the sectional door in upward and downward directions. The operator includes a motor for selectively rotating a drive shaft in two directions, a drive wheel on the drive shaft for rotating the drive train in one direction when the motor rotates the drive shaft in one direction, and a coupler on the drive shaft rotating the drive wheel when located in a first position and directly engaging and rotating the drive gear in the other direction when located in a second position. The design of this system extends a torque tube through the operator housing and is best installed during initial installation. To retrofit this operator to an existing door system, the tension must be removed from the counterbalance system and the counterbalance system must be disassembled to allow the torque tube to be extended axially through the operator housing. Afterward, the counterbalance system must be reassembled and tension reapplied to the counterbalance spring.
In another known design, a jack shaft garage door operator is used for positively opening and closing a garage door and includes a jack shaft garage door operator drive having an electric motor. The motor is connected to a jack shaft garage door operator transmission. The transmission includes an opening flexible link storage unit or cable drum having an open flexible link cable drive wrapped around it. Also connected to the jack shaft is a second cable drum having a closing flexible link or closing cable wound in the opposite direction from the opening cable. A compressive force transmitting member, which includes a quick turn bracket, couples the closing cable to the garage door and is itself connected to an upper portion of the garage door to transmit a positive closing force to the garage door throughout its entire travel as the closing cable is drawn in and the opening cable is paid out under the operation of the electric motor. While this device appears to have the ability to be installed without removing tension from and disassembling the counterbalance system, it requires a substantial amount of side room adjacent the door opening to install the operator on the end of the drive tube. Depending upon the length of drive tube extending outside the drive tube support bearing, one may need to provide an extension or replace the drive tube with a longer tube to retrofit this operator.
In yet another design known in the industry, an operator system for a counterbalanced door includes a rodless fluid cylinder that has a cylinder body and rodless piston adapted for reciprocation in the cylinder body. A carriage, which is adapted for reciprocation externally along the length of the cylinder body, is secured to the piston. A link member connects the cylinder carriage to a door or to a torsion bar for the door. A control circuit is provided for controlling the operation of the fluid cylinder and hence, the position of the door. This pneumatic system requires the torque tube to be inserted through the drive portion of the operator requiring the counterbalance system to have the tension removed and disassembled to facilitate installation.
In still another design known in the industry, an automatic opener for a sectional door includes a drive unit mounted adjacent to the door drive shaft having a reversible motor, a gear linkage for translating rotation of the motor drive shaft into rotation of the sectional door drive shaft, and a clutch which permits the gear linkage to be manually temporarily disengaged from the motor drive shaft. The drive unit is supported within a housing that is connected to an adjustable wall bracket mounting base that is fixed to a wall adjacent the sectional door. A spring biased lever attached near a lower end of the sectional door pivots in response to slack in a door cable to automatically lock the door when it is completely shut. The locking mechanism automatically unlocks the door either when the drive unit is actuated to open the sectional door or when the clutch is utilized to disengage the gear linkage from the motor drive shaft. Chains and sprockets are used to transmit power from the operator to the torque tube. Unless the counterbalance system is installed with the driven gear in place, the counterbalance system must have the tension removed and disassembled to install the operator.
Therefore, it is desirable to have a compact operator that does not require additional space outside the confines of an ordinary counterbalance system and may be retrofitted to an existing door system without disassembling the system's counterbalance system.